linux-kernel - [PATCH 4.14 07/36] cifs: integer overflow in in SMB2

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Date:   Fri, 28 Dec 2018 12:52:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Steve French <stfrench@...rosoft.com>,
        Aurelien Aptel <aaptel@...e.com>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 07/36] cifs: integer overflow in in SMB2_ioctl()

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

commit 2d204ee9d671327915260071c19350d84344e096 upstream

The "le32_to_cpu(rsp->OutputOffset) + *plen" addition can overflow and
wrap around to a smaller value which looks like it would lead to an
information leak.

Fixes: 4a72dafa19ba ("SMB2 FSCTL and IOCTL worker function")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Reviewed-by: Aurelien Aptel <aaptel@...e.com>
CC: Stable <stable@...r.kernel.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/smb2pdu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 69309538ffb8..1581e8668b09 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2020,14 +2020,14 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
 	/* We check for obvious errors in the output buffer length and offset */
 	if (*plen == 0)
 		goto ioctl_exit; /* server returned no data */
-	else if (*plen > 0xFF00) {
+	else if (*plen > rsp_iov.iov_len || *plen > 0xFF00) {
 		cifs_dbg(VFS, "srv returned invalid ioctl length: %d\n", *plen);
 		*plen = 0;
 		rc = -EIO;
 		goto ioctl_exit;
 	}
 
-	if (get_rfc1002_length(rsp) < le32_to_cpu(rsp->OutputOffset) + *plen) {
+	if (get_rfc1002_length(rsp) - *plen < le32_to_cpu(rsp->OutputOffset)) {
 		cifs_dbg(VFS, "Malformed ioctl resp: len %d offset %d\n", *plen,
 			le32_to_cpu(rsp->OutputOffset));
 		*plen = 0;
-- 
2.19.1